Interactive processing apparatus having natural language interfacing capability, utilizing goal frames, and judging action feasibility

ABSTRACT

A user goal extracting unit extracts a user goal from an input statement 10 entered by a user. A system goal determining unit 15 determines a system goal in accordance with the user goal. A goal frame generating unit 17 generates a goal frame based on an action sequence knowledge corresponding to the system goal. An action feasibility judging unit 19 sets arguments for, and judges the feasibility of, an action in the goal frame. If the action is judged to be feasible, the action feasibility judging unit 19 outputs an action command to an external application 20. If the action is not judged to be feasible, the action feasibility judging unit 19 outputs a new system goal to the goal frame generating unit 17. The external application 20 outputs a result of execution of the action.

This application is the national phase under 35 U.S.C. § 371 of priorPCT International Application No. PCT/JP96/02787, which has anInternational filing date of Sept. 26, 1996, which designated the UnitedStates of America, the entire contents of which are hereby incorporatedby reference.

TECHNICAL FIELD

The present invention relates to an interactive processing apparatus foruse in a man-machine interface using natural languages, and moreparticularly relates to an interactive processing apparatus capable ofperforming processes utilizing context information thereby allowingusers to interact with a system comprising the apparatus with a higherdegree of freedom than conventional one.

BACKGROUND ART

With a system having an interactive processing apparatus in aman-machine interface that uses natural language, the user first inputsdata to the system. The system responds to the user's input. In reply toresponses from the system, the user makes further entries in aninteractive manner, until the user achieves a goal. For the user tointeract with such an interactive processing apparatus smoothly andefficiently requires that two situations be suitably controlled: auser-initiated situation in which the user takes the initiative indemanding actions of the system, and a system-initiated situation wherethe system asks questions of the user to solicit responses andinformation. The requirement is met by use of a man-machine interfacecapable of controlling interaction with the user by setting appropriateaction goals fit for the user's intentions.

Japanese Patent Laid-Open Publication Number JP-A-63/153631, forexample, illustratively discloses an interactive processing apparatusfor use with the above-described type of man-machine interface usingnatural language. FIG. 1 is a function block diagram of the disclosedinteractive processing apparatus.

In FIG. 1, the reference numeral 1 is an information providing systemsuch as an information retrieval system that retrieves from storage thekind of information that is just fit for the user's needs; 2 isinformation output by the information providing system 1; 3 is an inputstatement in natural language entered by a user; 4 is natural languageinterpreting means for interpreting the meaning of the input statement 3in natural language; 5 is command generating means for generatingcommands to the information providing system 1; 6 is topic managingmeans for extracting objects attracting the user's attention from theinformation output by the information providing system 1 in response tothe command generated from the command generating means 5, the topicmanaging means further managing the extracted objects to be referencedduring the interpretation by the natural language interpreting means 4;and 7 is object storing means for storing the objects currentlyattracting the user's attention and managed by the topic managing means6 as well as a history of such objects.

In the conventional interactive processing apparatus outlined above,commands from the information providing system 1 corresponding to inputstatements 3 in natural language entered by the user allow the user tointeract with the system. Where objects attracting the user's attentionare extracted and stored in the object storing means 7, any of theseobjects may be retrieved and used in context analysis. The feature isintended to facilitate making interpretations in the context andminimize interpretive errors, thus rendering interaction smoother.

What characterizes the conventional interactive processing apparatusabove is that it has the information providing system 1 generating thecommands corresponding to the input statements 3 in natural languageentered by the user and that the apparatus simply carries out thecommands thus generated. There are no action goals set for the system,and control is not switched from the user-initiated to thesystem-initiated interactive situation. This results in the inability ofthe system to maintain smooth interaction if the information for thesystem to act on is insufficient or if any input statement 3 from theuser contains an error.

Natural language input entails frequent uses of abbreviations andreferring expressions. To identify what is abbreviated or referred torequires that the user reenter in more specific and substantive termswhat is curtailed or referenced. But an interactive session calling onthe user frequently to confirm what has already been input does notreally amount to an "interaction" with a tolerable degree of freedom.Hence the need for the system to supplement what is abridged or impliedin accordance with the context of interaction. What is noticeable hereis that abbreviations or referring expressions do not necessary point toany object attracting the user's attention. The substance ofabbreviations or references may or many not appear in the immediatelypreceding speech. There may exist a plurality of supplementarycandidates in the context. Furthermore, there are no fixed rules bywhich to determine one of any number of supplementary candidates; therules vary dynamically with the interactive situation. This requirescontrolling two things: determining whether or not to providesupplementation based on context information, and determining the rulesby which to select the contents of the supplement if such a supplementis judged to be necessary.

One disadvantage of the conventional interactive processing apparatusdisclosed in Japanese Patent Laid-Open Publication Number JP-A-63/153631is that because the apparatus deals with only the objects attracting theuser's attention, it is incapable of supplementing abbreviatedconditions, among others, in information retrieval.

The disadvantage above appears to be circumvented illustratively by aninteractive processing apparatus disclosed by Japanese Patent Laid-OpenPublication Number JP-A-1/222326. This conventional interactiveprocessing apparatus retains history information about input and outputstatements employed since the beginning of an interactive session. Whenthe intention of an input statement from the user is interpreted by agiven set of rules for interpretation, an abbreviation is supplementedby referring to the history information, whereby the user's intention isdetermined.

One disadvantage of the conventional interactive processing apparatusdescribed above is that in supplementing abbreviations based on thehistory of interaction, the apparatus is incapable of dynamicallyvarying the rules for selective supplementation depending on theinteractive situation.

It is the therefore an object of the present invention to overcome theabove and other deficiencies and disadvantages of the prior art and toprovide an interactive processing apparatus capable of setting suitableaction goals for a system on the basis of a user's intentions, therebyappropriately controlling the initiative of interaction between the userand the system.

It is another object of the present invention to provide an interactiveprocessing apparatus capable of dynamically controlling rules forselecting context information during interaction on the basis of theinteractive situation, thereby contextually processing abbreviations orreferring expressions that may appear in input statements in naturallanguage entered by the user.

DISCLOSURE OF THE INVENTION

In accordance with a preferred embodiment according to the presentinvention, an interactive processing apparatus comprises a user goalextracting unit for extracting, from a user-entered input statement innatural language, a user goal expressing the intention of the inputstatement defined by a user goal knowledge so as to generate a semanticrepresentation of the input statement, an interaction history storageunit for storing the semantic representation of the input statement, asystem goal determination unit for determining a system goalcorresponding to the user goal defined by a system goal knowledgeconstituting an action goal of a system, a goal frame generating unitfor generating a goal frame made up of the system goal and a systemaction sequence needed to achieve the system goal defined by an actionsequence knowledge, a goal frame storage unit for storing the goal framethus generated, an action feasibility judging unit for retrieving asemantic representation from the interaction history storage unit inorder to set arguments for, and judge feasibility of, the action in thegoal frame held by the goal frame storage unit, the action feasibilityjudging unit generating a new system goal if the action is not judged tobe feasible, the action feasibility judging unit outputting an actioncommand if the action is judged to be feasible, the action command beingexecuted by an external application, and a next action determining unitfor determining the next action of the system in accordance with theresult of the action command execution by the external application. Theinteractive processing apparatus of the above configuration sets anappropriate action goal of the system based on the user's intentions,thereby suitably controlling the initiative of interactive processingbetween the user and the system.

In the interactive processing apparatus as another preferred embodimentaccording to the present invention, the interaction history storage unitmay store in a stacked fashion semantic representations of user goalsand input statements output by the user goal extracting unit, as well assemantic representations output by the next action determining unit. Ifthere exists an action for which arguments cannot be set because of anincomplete semantic representation in an input statement, the actionfeasibility judging unit may consecutively retrieve semanticrepresentations stacked in the interaction history storage unit so as toset arguments for the action. This structure makes it possible tosupplement referring, pronoun or abbreviated expressions included in theuser-entered natural language.

In the interactive processing apparatus as another preferred embodimentaccording to the present invention, the interaction history storage unitmay give a score to each of data items in semantic representations, andthe action feasibility judging unit may set arguments for actions inaccordance with the scores given to the data items. This structureallows supplementary candidates to be selected dynamically depending onthe interactive situation.

In the interactive processing apparatus as another preferred embodimentaccording to the present invention, the interaction history storage unitmay control the scores given to the data items in the semanticrepresentations through the use of a time function. This structureallows rules of selective supplementation to be controlled dynamicallydepending on the interactive situation.

Other objects, features and advantages of the present invention willbecome apparent in the following description and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a function block diagram of a conventional interactiveprocessing apparatus;

FIG. 2 is a function block diagram of an interactive processingapparatus practiced as a first embodiment of the present invention;

FIG. 3 is a view of a user goal knowledge for use with the firstembodiment of the present invention;

FIG. 4 is a view of a user goal and semantic representations of aspeech;

FIG. 5 is a view of a system goal knowledge for use with the firstembodiment of the present invention;

FIG. 6 is a view of an action sequence knowledge for use with the firstembodiment of the present invention;

FIG. 7 is a view of a goal frame for use with the first embodiment ofthe present invention;

FIG. 8 is a view of an interaction between a user and an interactiveprocessing apparatus practiced as a second embodiment of the presentinvention;

FIG. 9 is a view of a user goal and a semantic representation of aspeech generated by a user goal generating unit of the second embodimentof the present invention;

FIG. 10 is a view of user goals and semantic representations of speecheswhich are retained by an interaction history storage unit of the secondembodiment;

FIG. 11 is a view of a user goal and a semantic representation of aspeech which are generated by a user goal extracting unit of aninteractive processing apparatus practiced as a third embodiment of thepresent invention, the data item in the semantic representation beinggiven a score;

FIG. 12 is a view of user goals and semantic representations of speecheswhich are retained by an interaction history storage unit of the thirdembodiment of the present invention;

FIG. 13 is a view of a user goal and semantic representations ofspeeches which are retained by an interaction history storage unit ofthe third embodiment of the present invention; and

FIG. 14 is a view of user goals and semantic representations of speecheswhich are retained by an interaction history storage unit of aninteractive processing apparatus practiced as a fourth embodiment of thepresent invention, the interaction history storage unit controllingscores given to the data items in the semantic representations throughthe use of a time function.

BEST MODE FOR EMBODYING THE INVENTION

The best mode for carrying out the present invention will now bedescribed in detail with reference to the accompanying drawings.

First Embodiment

FIG. 2 is a function block diagram of an interactive processingapparatus practiced as the first embodiment of the present invention. InFIG. 2, the reference numeral 10 is an input statement in naturallanguage entered by a user, 11 is a user goal knowledge composed of usergoals that define intentions of input statements 10 in natural language,12 is a user goal extracting unit which refers to the user goalknowledge 11 so as to extract a user goal from the input statement 10entered by the user, thereby generating a semantic representation of theinput statement 10, 13 is an interaction history storage unit whichretains user goals and semantic representations from the user goalextracting unit 12, as well as semantic representations coming from anext action determining unit 21 to be described later, 14 is a systemgoal knowledge that defines system goals constituting action goals of asystem, and 15 is a system goal determining unit for determining, fromthe system goal knowledge 14, a system goal corresponding to the usergoal from the user goal extracting unit 12.

The reference numeral 16 is an action sequence knowledge that definessystem action sequences needed to achieve system goals, 17 is a goalframe generating unit for retrieving from the action sequence knowledge16 an action sequence knowledge node corresponding to a system goalwhich is input either from the system goal determining unit 15 or froman action feasibility judging unit 19 to be defined later, the goalframe generating unit 17 further generating a goal frame pairing thesystem goal with the corresponding action sequence knowledge node, and18 is a goal frame storage unit for storing goal frames output by thegoal frame generating unit 17.

The reference numeral 19 stands for an action feasibility judging unitfor retrieving a semantic representation of a speech from theinteraction history storage unit 13 in order to set arguments for, andjudge feasibility of, an action in a goal frame being held by the goalframe storage unit 18. The action feasibility judging unit 19 outputs anaction command if the action is judged to be feasible, the actionfeasibility judging unit 19 generates a new system goal if the action isnot judged to be feasible, the newly generated system goal being outputto the goal frame generating unit 17. The reference numeral 20 indicatesan external application driven upon receipt of an action command fromthe action feasibility judging unit 19, the external application 20further outputting a result of execution of the action. The referencenumeral 21 represents a next action determining unit for determining, inresponse to the result of action execution output by the externalapplication 20, the action to be executed next in the action sequence ofa goal frame being held by the goal frame storage unit 18, the nextaction determining unit 21 further outputting to the interaction historystorage unit 13 a semantic representation acquired from the result ofthe action execution.

Next, a description will now be given of the operation of theinteractive processing apparatus as the first embodiment.

FIG. 3 is a view showing a typical content of the user goal knowledge11. In this example, users'speeches such as "Tell me <NAME> <ATTRIBUTENAME> and "I want to know <NAME> <ATTRIBUTE NAME> are togetherassociated with a user goal "GET₋₋ AVALUE" (I want attribute value). The<NAME> and <ATTRIBUTE> are arguments needed to execute a system action,to be described later.

The user goal extracting unit 12 performs syntax analysis on a user'snatural language speech entered as an input statement 10, such as "Howmuch is the admission fee of Kenchoji Temple?," and generatesaccordingly a user goal together with semantic representations of thespeech, i.e., [USER GOAL]:=GET₋₋ AVALUE, <NAME>:=KENCHOJI TEMPLE,<ATTRIBUTE NAME>:=ADMISSION FEE, as shown in FIG. 3. The user goal andthe semantic representations of the speech are sent to the interactionhistory storage unit 13 for storage therein and are also input to thesystem goal determining unit 15.

FIG. 5 shows a typical content of the system goal knowledge 14. In thisexample, the system goal knowledge 14 defines a system goal "GIVE₋₋AVALUE" signifying the action of "presenting the user with an attributevalue," and a system goal "RETRIEVE₋₋ RECORD" signifying the action of"presenting the user with a record which meets the conditions and whichis retrieved from a database." These system goals are associated withuser goals "GET₋₋ AVALUE" and "GET₋₋ RECORD" respectively.

The system goal determining unit 15 determines, based on the system goalknowledge 14, a system goal corresponding to a user goal sent from theuser goal extracting unit 12, and outputs the system goal thusdetermined to the goal frame generating unit 17. Illustratively, if auser goal "GET₋₋ AVALUE" is received from the user goal extracting unit12, the system goal determining unit 15 determines the system goal"GIVE₋₋ AVALUE" selectively from the system goal knowledge 14 andoutputs the selected system goal.

FIG. 6 shows a typical content of the action sequence knowledge 16. Inthis example, lines 1 through 4 declare system actions. Line 1 declaresan action having two arguments, <NAME> and <ATTRIBUTE NAME>. Eachargument mandatory for execution of the action is defined with a symbol"!" prefixed to the argument name. Line 5 and subsequent lines define asequence of actions needed to achieve the system goal of, say, "GIVE₋₋AVALUE." In this case, the first action to be started is"retrieve--avalue." If the result of execution of the action is"ILLEGAL₋₋ ATTRIBUTE," then the next action is defined as "inform₋₋illegal", if the result is "NONE," the next action is defined as"inform₋₋ none, if the result is "AVALUE," the next action is defined as"inform₋₋ avalue."

Given a system goal from the system goal determining unit 15, the goalframe generating unit 17 obtains from the action sequence knowledge 16an action sequence knowledge node corresponding to the system goal so asto generate a goal frame. FIG. 7 depicts a typical goal frame generatedby the goal frame generating unit 17 when the latter receives a systemgoal "GIVE₋₋ AVALUE" from the system goal determining unit 15. Actionsequence knowledge nodes obtained from the action sequence knowledge 16constitute a tree structure wherein each branch is labeled with theresult of execution of an action. The first node of the tree isestablished as the action to be processed (hereinafter referred to asthe current action).

Goal frames thus generated and output by the goal frame generating unit17 are retained illustratively in a stacked manner in the goal framestorage unit 18. The first goal frame in the stack (hereinafter referredto as the current goal frame) is processed subsequently.

The action feasibility judging unit 19 retrieves semanticrepresentations of a speech from the interaction history storage unit 13in order to set arguments for the current action of the current goalframe held by the goal frame storage unit 18. Illustratively, the actionfeasibility judging unit 19 retrieves the semantic representations inFIG. 4 from the interaction history storage unit 13 so as to setarguments <NAME>:=KENCHOJI TEMPLE and <ATTRIBUTE NAME>: =ADMISSION FEEfor the current action "retrieve₋₋ avalue" of the goal frame in FIG. 7.The current action is judged to be feasible when all its mandatoryarguments have been set. In such a case, the action feasibility judgingunit 19 outputs an action command to the external application 20. If notall its mandatory arguments have been set, the action is judged to beunfeasible. In that case, the action feasibility judging unit 19 outputsto the goal frame generating unit 17 a system goal (e.g., "GET₋₋ATTNAME") for which mandatory arguments are to be acquired from theuser.

The external application 20 may illustratively be an informationretrieval system tapping a database, a hotel reservation system, or aairline ticket reservation system. Given an action command from theaction feasibility judging unit 19, the external application 20 executesthe action command and outputs the result of the execution. For example,if an action command "retrieve₋₋ avalue (KENCHOJI TEMPLE, ADMISSIONFEE)" is received from the action feasibility judging unit 19, theexternal application 20 retrieves applicable data from a touristinformation database. If the conditions for data retrieval are notappropriate, the application 20 outputs "ILLEGAL₋₋ ATTRIBUTE", if theapplicable data is not available, the application 20 outputs "NONE", ifthe applicable data is obtained, the application 20 outputs "AVALUE."Each output is sent to the next action determining unit 21. The externalapplication 20 may illustratively present the user with the result ofdata retrieval or the booking status in synthesized voice or in agraphical user interface (GUI) format.

On the basis of the result of command execution from the externalapplication 20, the next action determining unit 21 selects theapplicable branch (i.e., next action) of an action sequence knowledgetree in the goal frame storage unit 18, and regards the selected branchas the current action. For example, suppose that an action commandΘretrieval₋₋ avalue (KENCHOJI TEMPLE, ADMISSION FEE)" is received fromthe action feasibility judging unit 19 and that the external application20 outputs the result of command execution "AVALUE: =[<ADMISSIONFEE>:=300]. In that case, the next action determining unit 21 outputs tothe interaction history storage unit 13 the semantic representation<ADMISSION FEE> contained in the execution result. Furthermore, the nextaction determining unit 21 selects the branch labeled "AVALUE" on theaction knowledge tree in FIG. 7 to determine "inform.sub. avalue" as thenext action and regard it as the current action. If the branch to beselected does not exist on the action knowledge tree of the current goalframe, that means all actions for achieving the current goal frame havebeen executed. In that case, the current goal frame is removed from thegoal frame storage unit 18.

The action feasibility judging unit 19 is activated every time adifferent current action is set in the goal frame storage unit 18. Thusstarted, the action feasibility judging unit 19 achieves the system goaldetermined by the system goal determining unit 15.

As described above, the interactive processing apparatus as the firstembodiment of the present invention extracts a user goal from a user'sspeech, determines a system goal corresponding to the user goal, andexecutes and achieves a system action sequence applicable to the systemgoal. If the action cannot be executed, a new system goal is generatedand the action corresponding to the new goal is carried out. In thismanner, the first embodiment sets appropriate system action goals basedon the user's intentions in order to optimally control the initiative ofinteraction between the user and the system.

Second Embodiment

In the preceding description, the interactive processing apparatus ofthe first embodiment was shown getting the interaction history storageunit 13 simply to retain user goals together with semanticrepresentations from the user goal extracting unit 12, as well assemantic representations coming from the next action determining unit21. It was shown that the action feasibility judging unit 19 retrievessemantic representations of the speech from the interaction historystorage unit 13 to set arguments necessary for executing the action ofthe current goal frame held by the goal frame storage unit 18, and thatthe judging unit 19 judges whether the action is feasible. It wasfurther shown that if the action is feasible, the action feasibilityjudging unit 19 outputs the action command, and that if the action isnot feasible, the action feasibility judging unit 19 generates a newsystem goal and outputs the goal to the goal frame generating unit 17.

With the second embodiment of the present invention, by contrast, theinteraction history storage unit 13 may retain in a stacked fashion usergoals together with semantic representations from the user goalextracting unit 12 as well as semantic representations from the nextaction determining unit 21. Where there is an action for which theaction feasibility judging unit 19 cannot set arguments because of anincomplete semantic representation in any input statement, the stackedsemantic representations may be retrieved successively from theinteraction history storage unit 13 until the necessary arguments areset for the action.

The interactive processing apparatus practiced as the second embodimentof the present invention may have the same configuration as the firstembodiment shown in FIG. 2. With the exception of the interactionhistory storage unit 13 and action feasibility judging unit 19, the usergoal knowledge 11, user goal extracting unit 12, system goal knowledge14, system goal determining unit 15, action sequence knowledge 16, goalframe generating unit 17, goal frame storage unit 18, externalapplication 20, and next action determining unit 21 all work in the samemanner as their counterparts of the first embodiment.

Next, a description will now be given of the operation of theinteractive processing apparatus as the second embodiment. The ensuingdescription will center on the workings of the interaction historystorage unit 13 and action feasibility judging unit 19.

FIG. 8 shows a typical interaction between a user and the secondembodiment of the present invention. As indicated, the input of a user'sspeech U1, "How much is the admission fee of Kenchoji Temple?" activatesthe interactive processing apparatus as described in connection with thefirst embodiment. The external application 20 presents the user with asystem response S1, "300 yen" illustratively in synthesized voice. Theuser's next speech U2, "What about Enkakuji Temple?" causes the usergoal extracting unit 12 to generate a user goal and a semanticrepresentation of the speech shown in FIG. 9, i.e., [USER GOAL]:=GET₋₋AVALUE, <NAME>:=ENKAKUJI TEMPLE.

The user goal together with the semantic representation of the user'sspeech output by the user goal extracting unit 12, i.e., [USERGOAL]:=GET₋₋ AVALUE, <NAME>:=ENKAKUJI TEMPLE, and the user goal togetherwith the semantic representations corresponding to the user's speech U1and system response S1, i.e., [USER GOAL]:=GET₋₋ AVALUE, <NAME>:=KENCHOJI TEMPLE, <ATTRIBUTE NAME>:=ADMISSION FEE, <ADMISSION FEE>:=300,are stacked in the interaction history storage unit 13 as shown in FIG.10.

The system goal determining unit 15, goal frame generating unit 17 andgoal frame storage unit 18 work in the same manner as their counterpartsof the first embodiment. A typical current goal frame generated by thesecond embodiment is as shown in FIG. 7.

The action feasibility judging unit 19 retrieves semanticrepresentations of a speech from the interaction history storage unit 13so as to set arguments for the current action "retrieve₋₋ avalue." Here,a mandatory argument <NAME> is set as "ENKAKUJI TEMPLE" based on thefirst element in the stack of FIG. 10, whereas a mandatory argument<ATTRIBUTE NAME> cannot be set on the basis of the first element in thestack. In that case, the action feasibility judging unit 19 sets thelatter argument by successively retrieving stacked elements from theinteraction history storage unit 13. As a result, the mandatory argument<ATTRIBUTE NAME> is set as "ADMISSION FEE." When all mandatory argumentshave been set in the manner described, the action feasibility judgingunit 19 judges that the current action is now feasible, and outputs theappropriate action command to the external application 20.

As described above, the interactive processing apparatus as the secondembodiment of the present invention has the interaction history storageunit 13 accommodating in a stacked format user goals together withsemantic representations of speeches coming from the user goalextracting unit 12, as well as semantic representations received fromthe next action determining unit 21. When there is an action for whicharguments cannot be set because of an incomplete semanticrepresentation, the action feasibility judging unit 19 retrievesconsecutively stacked elements from the interaction history storage unit13 until all necessary arguments have been set for the action. In thismanner, there is the effect to provide the interactive processingapparatus is capable of supplementing, during interaction with a user,referring, pronoun or abbreviated expressions included in naturallanguage speeches entered by the user.

Third Embodiment

The interactive processing apparatus as the second embodiment was showngetting the interaction history storage unit 13 to accommodate in astacked format user goals together with semantic representations comingfrom the user goal extracting unit 12, as well as semanticrepresentations received from the next action determining unit 21. Itwas also shown that where there exists an action for which argumentscannot be set because of an incomplete semantic representation of aninput statement, the action feasibility judging unit 19 consecutivelyretrieves stacked elements from the interaction history storage unit 13until all necessary arguments have been set for the action.Alternatively, the interaction history storage unit 13 of the thirdembodiment may give a score to each of the data items in semanticrepresentations, so that the action feasibility judging unit 19 may setarguments for any action in accordance with the score given to each dataitem.

The interactive processing apparatus practiced as the third embodimentof the present invention may have the same configuration as the firstembodiment in FIG. 2. With the exception of the interaction historystorage unit 13 and action feasibility judging unit 19, the user goalknowledge 11, user goal extracting unit 12, system goal knowledge 14,system goal determining unit 15, action sequence knowledge 16, goalframe generating unit 17, goal frame storage unit 18, externalapplication 20, and next action determining unit 21 all work in the samemanner as their counterparts of the first or second embodiment.

Next, a description will be given of the operation of the interactiveprocessing apparatus as the third embodiment. The ensuing descriptionwill center on the workings of the interaction history storage unit 13and action feasibility judging unit 19.

Upon receipt of a user goal and a semantic representation of a speechsuch as those in FIG. 9 from the user goal extracting unit 12, theinteraction history storage unit 13 gives an initial score to the datain the semantic representation as shown in FIG. 11. For example, <NAME5> signifies that a score of 5 is given to "<NAME>:=ENKAKUJI TEMPLE."Thereafter, the interaction history storage unit 13 places the user goaland semantic representation into a stack.

The action feasibility judging unit 19 retrieves from the interactionhistory storage unit 13 semantic representations whose data items aregiven a score each, and sets arguments for the current action"retrieve₋₋ avalue." In that case, the action feasibility judging unit19 sets arguments only if the score of a given semantic representationexceeds a predetermined threshold value.

Suppose that, as shown in FIG. 12, a score of 5 is given to the firstelement in the stack, <NAME>:=ENKAKUJI TEMPLE, and a score of 3 is givento each of the last elements in the stack, <NAME>:=KENCHOJI TEMPLE and<ATTRIBUTE NAME>: =ADMISSION FEE. If the predetermined threshold valueis 3, the arguments for the current action "retrieve₋₋ avalue" are setin the same manner as with the second embodiment. If the threshold valueis 5, the mandatory argument <NAME> is set in the same manner as thesecond embodiment but the mandatory argument <ATTRIBUTE NAME> is notset.

The action feasibility judging unit 19 judges an action unfeasible ifthe action is one for which the mandatory arguments have not all beenset. In that case, the action feasibility judging unit 19 outputs to thegoal frame generating unit 17 a system goal for acquiring the mandatoryarguments from the user, such as "GET₋₋ ATTNAME." The score for eachsemantic representation used in setting the arguments is incremented bya predetermined value. Illustratively, if the element <ATTRIBUTE NAME 3>in the stack in FIG. 12 is used to set an argument, the score for thesemantic representation is incremented by 1 (i.e., <ATTRIBUTE NAME 4>).

As described above, the interactive processing apparatus as the thirdembodiment has the interaction history storage unit 13 giving a score toeach of the data items in semantic representations so that the actionfeasibility judging unit 19 sets arguments for an action in accordancewith the score given to each data item. This feature allows theinteractive processing apparatus dynamically to select candidates forsupplementing incomplete expressions depending on the interactivesituation.

Fourth Embodiment

The interactive processing apparatus as the third embodiment describedabove was shown giving a score to each of data items in semanticrepresentations so that arguments for actions may be set according tothe scores. Alternatively, the interactive processing apparatus as thefourth embodiment may use a time function in controlling the scoresgiven to each of the data items in semantic representations. Theinteractive processing apparatus practiced as the fourth embodiment ofthe present invention may have the same configuration as the firstembodiment shown in FIG. 2. With the exception of the interactionhistory storage unit 13, the components of the fourth embodiment work inthe same manner as their counterparts of the third embodiment.

Next, a description will be given of the operation of the interactiveprocessing apparatus as the fourth embodiment. The ensuing descriptionwill center on the workings of the interaction history storage unit 13.

Upon receipt of a user goal and a semantic representation of a speechsuch as those in FIG. 9 from the user goal extracting unit 12, theinteraction history storage unit 13 gives an initial score of 5 to thedata in the semantic representation as shown in FIG. 11. The user goaland the semantic representation together with the score are placed intoa stack. Suppose that, as shown in FIG. 13, the stack already retainssemantic representations with scores and 5 and 4, e.g., <ADMISSION FEE5>:=300, <NAME 4>:=KENCHOJI TEMPLE, and <ATTRIBUTE NAME 4>:=ADMISSIONFEE. In such a case, the scores 5 and 4 may be changed by use of a timefunction. The time function may illustratively be S(n)=1.5n, i.e., afunction of the number of times (n) interaction has taken place betweenthe user and the interactive processing apparatus since semanticrepresentations began being placed into the stack.

The result is that, as shown in FIG. 14, the semantic representationsheld in the stack have their scores changed, e.g., <ADMISSION FEE2.5>:=300, <NAME 0>:=KENCHOJI TEMPLE, and <ATTRIBUTE NAME O>:=ADMISSIONFEE. In addition, a new user goal together with the associated semanticrepresentation, i.e., [USER GOAL]:=GET₋₋ AVALUE and <NAME 5>: =ENKAKUJITEMPLE, is placed into the stack.

As described above, the interactive processing apparatus as the fourthembodiment utilizes a time function in controlling the scores that theinteraction history storage unit 13 has given to the data items insemantic representations. This feature allows the interactive processingapparatus dynamically to control the rules of selective supplementationfor incomplete expressions depending on the interactive situation.

INDUSTRIAL APPLICABILITY

As described, the interactive processing apparatus according to thepresent invention is adapted advantageously to a man-machine interfacethat allows a system to interact repeatedly in natural language with auser, i.e., the system responding to the user's input and the userresponding again to the system response, and so on, until the user'sgoal is achieved. In particular, the inventive interactive processingapparatus sets appropriate actions for the system to perform on thebasis of the user's intentions, thus optimally controlling theinitiative of interaction between the user and the system. Preferably,the interactive processing apparatus of the present invention maysupplement referring, pronoun or abbreviated expressions in naturallanguage statements entered by the user. The inventive interactiveprocessing apparatus may dynamically select candidates for supplementingthe user's incomplete expressions depending on the interactivesituation. Furthermore, the inventive interactive processing apparatusmay control the rules of selective supplementation for incompleteexpressions from the user.

We claim:
 1. An interactive processing apparatus comprising:a user goalextracting unit for referring to a user goal knowledge composed of usergoals for defining intentions of input statements in natural languageentered by a user, in order to extract a user goal from each inputstatement, thereby generating a semantic representation of the inputstatement; an interaction history storage unit for storing semanticrepresentations of user goals and input statements output by the usergoal extracting unit, as well as semantic representations output by anext action determining unit to be defined later; a system goaldetermining unit for determining a system goal corresponding to a givenuser goal from a system goal knowledge composed of system goalsconstituting action goals of a system; a goal frame generating unit forretrieving from an action sequence knowledge a system action sequenceknowledge node corresponding to a system goal which is input either fromthe system goal determining unit or from an action feasibility judgingunit to be defined later, the sequence knowledge being composed ofsystem action sequence knowledge nodes needed to achieve system goals,the goal frame generating unit further generating a goal frame pairingthe system goal with the corresponding system action sequence knowledgenode; a goal frame storage unit for storing goal frames output by thegoal frame generating unit; an action feasibility judging unit forretrieving a semantic representation from the interaction historystorage unit in order to set arguments for, and judge feasibility of,the action in a goal frame being held by the goal frame storage unit;the action feasibility judging unit outputting an action command if theaction is judged to be feasible; the action feasibility judging unitgenerating a new system goal if the action is not judged to be feasible,the newly generated system goal being output to the goal framegenerating unit; an external application driven upon receipt of anaction command from the action feasibility judging unit, the externalapplication further outputting a result of execution of the action; anda next action determining unit for determining, in response to theresult of action execution output by the external application, theaction to be executed next in the action sequence of a goal frame beingheld by the goal frame storage unit, the next action determining unitfurther outputting to the interaction history storage unit a semanticrepresentation acquired from the result of the action execution.
 2. Aninteractive processing apparatus according to claim 1, wherein theinteraction history storage unit stores in a stacked fashion semanticrepresentations of user goals and input statements output by the usergoal extracting unit, as well as semantic representations output by thenext action determining unit; andwherein, if there exists an action forwhich arguments cannot be set because either a referring a pronoun or anabbreviated expression is included in an input statement in naturallanguage entered by a user, the action feasibility judging unitconsecutively retrieves semantic representations stacked in theinteraction history storage unit so as to set arguments for the action.3. An interactive processing apparatus according to claim 1, wherein theinteraction history storage unit gives a score to each of data items insemantic representations, andwherein the action feasibility judging unitsets arguments for actions in accordance with the scores given to thedata items.
 4. An interactive processing apparatus according to claim 3,wherein the interaction history storage unit controls the scores givento the data items in the semantic representations based on the use of atime function.